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Itishree Mishra XII A. Computer networking devices are units that mediate data in a computer network. Computer networking devices are also called network.

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Presentation on theme: "Itishree Mishra XII A. Computer networking devices are units that mediate data in a computer network. Computer networking devices are also called network."— Presentation transcript:

1 Itishree Mishra XII A

2 Computer networking devices are units that mediate data in a computer network. Computer networking devices are also called network equipment, Intermediate Systems (IS)or Interworking Unit (IWU). Units which are the last receiver or generate data are called hosts or data terminal equipment. Computer networking devices are units that mediate data in a computer network. Computer networking devices are also called network equipment, Intermediate Systems (IS)or Interworking Unit (IWU). Units which are the last receiver or generate data are called hosts or data terminal equipment.datahostsdata terminal equipmentdatahostsdata terminal equipment

3 Separating (connecting) networks or expanding network Separating (connecting) networks or expanding network e.g. repeaters, hubs, bridges, routers, switches, gatewayse.g. repeaters, hubs, bridges, routers, switches, gateways Remote access Remote access e.g. 56K Modems and ADSL modemse.g. 56K Modems and ADSL modems

4 Networks cannot be made larger by simply adding new computers and more cables Networks cannot be made larger by simply adding new computers and more cables Less efficient !!Less efficient !! Can install components to Can install components to segment (divide) large LAN to form smaller LANssegment (divide) large LAN to form smaller LANs connect LANsconnect LANs Required components Required components Repeaters, bridges, routers, switches or gatewaysRepeaters, bridges, routers, switches or gateways

5 Modem Modem RJ-45 RJ-45 Ethernet card Ethernet card Hub Hub Switch Switch Repeater Repeater Bridge Bridge Router Router Gateway Gateway

6 A MODEM is a computer peripheral that allows you to connect and communicate eith other computers via telephone lines. A MODEM is a computer peripheral that allows you to connect and communicate eith other computers via telephone lines.

7 MODEM stands for modulation and demodulation.MODEM stands for modulation and demodulation. Allow computers to communicate over a telephone lineAllow computers to communicate over a telephone line Enable communication between networks or connecting to the world beyond the LANEnable communication between networks or connecting to the world beyond the LAN

8 Cannot send digital signal directly to telephone line Cannot send digital signal directly to telephone line Sending end: MODulate the computers digital signal into analog signal and transmits Sending end: MODulate the computers digital signal into analog signal and transmits Receiving end: DEModulate the analog signal back into digital form Receiving end: DEModulate the analog signal back into digital form

9 1.Internal modems: The modems that are fixed within the computer. 2. EXTERNAL MODEMS: The modems that are connected externally to the computer.

10 MODEM converts digital signals to A/F (Audio Frequency) tones which are in the frequency range that the telephone lines can transmit and also it can convert transmitted tones back to digital information. MODEM converts digital signals to A/F (Audio Frequency) tones which are in the frequency range that the telephone lines can transmit and also it can convert transmitted tones back to digital information.

11 RJ 45 is the short for Registered jack 45. RJ 45 is an eight wire connector, which is commonly used to connect computers on the local area networks i.e., LANs especially Ethernets. (Ethernet is a LAN architechture developed by Xerox Corp along with DEC and Intel. It uses either bus or star topologyand suports data transfer rates upto 10 Mbps.)

12 Inserting an RJ-45 connector into its jack. RJ-45 jack.

13 Ethernet is a LAN architecture developed by Xerox corp. in association with DEC and Intel. Ethernet uses either bus or star topology and supports data transfer rates up to 10 mbps. The computers that are part of Ethernet, have to install a special card called Ethernet card.

14 An Ethernet card contains connections for either coaxial or twisted pair cables or both. An Ethernet card contains connections for either coaxial or twisted pair cables or both. Inserting Ethernet card in its slot on motherboard

15 Hub can be defined as one common point for connecting all the network devices. Various LAN segments are LAN connected to hub in order to organize the working of the network. A network hub connects the various ports of the optic fiber cable and helps establish a single network connection or segment.

16 The most common operation it performs is that it repeats all the information it receives and forward it to all PC terminals attached to it. The most common operation it performs is that it repeats all the information it receives and forward it to all PC terminals attached to it. This repetition of data results in unnecessary data traffic being sent to the network. Therefore the data is sent in bulk without the identification of its destination.

17 Limitations and Features Cannot link unlike segmentsCannot link unlike segments Cannot join segments with different access methods (e.g. CSMA/CD and token passing)Cannot join segments with different access methods (e.g. CSMA/CD and token passing) Do not isolate and filter packetsDo not isolate and filter packets Can connect different types of mediaCan connect different types of media The most economic way of expanding networksThe most economic way of expanding networks

18 A network switch is a small hardware device that joins multiple computers together within one local area network (LAN). Technically, network switches operate at layer two (Data Link Layer) of the OSI model. A network switch is a small hardware device that joins multiple computers together within one local area network (LAN). Technically, network switches operate at layer two (Data Link Layer) of the OSI model.

19 Network switches appear nearly identical to network hubs, but a switch generally contains more intelligence (and a slightly higher price tag) than a hub. Network switches appear nearly identical to network hubs, but a switch generally contains more intelligence (and a slightly higher price tag) than a hub. Unlike hubs, network switches are capable of inspecting data packets as they are received, determining the source and destination device of each packet, and forwarding them appropriately. Unlike hubs, network switches are capable of inspecting data packets as they are received, determining the source and destination device of each packet, and forwarding them appropriately. By delivering messages only to the connected device intended, a network switch conserves network bandwidth and offers generally better performance than a hub. By delivering messages only to the connected device intended, a network switch conserves network bandwidth and offers generally better performance than a hub.

20 A switch is a telecommunication device which receives a message from any device connected to it and then transmits the message only to the device for which the message was meant. This makes the switch a more intelligent device than a hub (which receives a message and then transmits it to all the other devices on its network). The network switch plays an integral part in most modern Ethernet LANs. A switch is a telecommunication device which receives a message from any device connected to it and then transmits the message only to the device for which the message was meant. This makes the switch a more intelligent device than a hub (which receives a message and then transmits it to all the other devices on its network). The network switch plays an integral part in most modern Ethernet LANs.

21 21 Advantages of Switches Switches divide a network into several isolated channels (or collision domains)Switches divide a network into several isolated channels (or collision domains) Reduce the possibility of collisionReduce the possibility of collision Collision only occurs when two devices try to get access to one channelCollision only occurs when two devices try to get access to one channel Can be solved by buffering one of them for later accessCan be solved by buffering one of them for later access Each channel has its own network capacityEach channel has its own network capacity Suitable for real-time applications, e.g. video conferencingSuitable for real-time applications, e.g. video conferencing Since isolated, hence secureSince isolated, hence secure Data will only go to the destination, but not othersData will only go to the destination, but not others

22 22 Limitations of Switches Although contains buffers to accommodate bursts of traffic, can become overwhelmed by heavy trafficAlthough contains buffers to accommodate bursts of traffic, can become overwhelmed by heavy traffic Device cannot detect collision when buffer fullDevice cannot detect collision when buffer full CSMA/CD scheme will not work since the data channels are isolated, not the case as in EthernetCSMA/CD scheme will not work since the data channels are isolated, not the case as in Ethernet Some higher level protocols do not detect errorSome higher level protocols do not detect error E.g. UDPE.g. UDP Those data packets are continuously pumped to the switch and introduce more problemsThose data packets are continuously pumped to the switch and introduce more problems

23 A repeater is an electronic device that receives a signal and retransmits it at a higher level or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances. A repeater is an electronic device that receives a signal and retransmits it at a higher level or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances.

24 In digital communication systems, a repeater is a device that receives a digital signal on an electromagnetic or optical transmission medium and regenerates the signal along the next leg of the medium. In electromagnetic media, repeaters overcome the attenuation caused by free-space electromagnetic-field divergence or cable loss. A series of repeaters make possible the extension of a signal over a distance. In digital communication systems, a repeater is a device that receives a digital signal on an electromagnetic or optical transmission medium and regenerates the signal along the next leg of the medium. In electromagnetic media, repeaters overcome the attenuation caused by free-space electromagnetic-field divergence or cable loss. A series of repeaters make possible the extension of a signal over a distance. Repeaters remove the unwanted noise in an incoming signal. Unlike an analog signal, the original digital signal, even if weak or distorted, can be clearly perceived and restored. With analog transmission, signals are restrengthened with amplifiers which unfortunately also amplify noise as well as information. Repeaters remove the unwanted noise in an incoming signal. Unlike an analog signal, the original digital signal, even if weak or distorted, can be clearly perceived and restored. With analog transmission, signals are restrengthened with amplifiers which unfortunately also amplify noise as well as information.

25 Has one input and one output Has one input and one output Used to isolate network traffic and computers Used to isolate network traffic and computers Has the intelligent to examine incoming packet source and destination addresses. Has the intelligent to examine incoming packet source and destination addresses. But cannot interpret higher- level informationBut cannot interpret higher- level information Hence cannot filter packet according to its protocolHence cannot filter packet according to its protocol

26 Bridges work at the Media Access Control Sub- layer of the OSI model. Routing table is built to record the segment no. of address. If destination address is in the same segment as the source address, stop transmit. Otherwise, forward to the other segment.

27 27 Differences Between Bridges and Repeaters

28 In a common configuration, routers are used to create larger networks by joining two network segments. In a common configuration, routers are used to create larger networks by joining two network segments. A router can be a dedicated hardware device or a computer system with more than one network interface and the appropriate routing software. All modern network operating systems include the functionality to act as a router. A router can be a dedicated hardware device or a computer system with more than one network interface and the appropriate routing software. All modern network operating systems include the functionality to act as a router. Routers will normally create, add, or divide on the Network Layer as they are normally IP-based devices. Routers will normally create, add, or divide on the Network Layer as they are normally IP-based devices.

29 As packets are passed from routers to routers, Data Link layer source and destination addresses are stripped off and then recreated As packets are passed from routers to routers, Data Link layer source and destination addresses are stripped off and then recreated Enables a router to route a packet from a TCP/IP Ethernet network to a TCP/IP token ring network Enables a router to route a packet from a TCP/IP Ethernet network to a TCP/IP token ring network Only packets with known network addresses will be passed - hence reduce traffic Only packets with known network addresses will be passed - hence reduce traffic Routers can listen to a network and identify its busiest part Routers can listen to a network and identify its busiest part Will select the most cost effective path for transmitting packets Will select the most cost effective path for transmitting packets

30 30 Routers are layer 3 devices which recognize network addressRouters are layer 3 devices which recognize network address Bridges are layer 2 devices which look at the MAC sublayer node addressBridges are layer 2 devices which look at the MAC sublayer node address Bridges forward everything they dont recognizeBridges forward everything they dont recognize Routers select the best pathRouters select the best path Distinguishing Between Bridges and Routers

31 Any device that translates one data format to another is called a gateway. Any device that translates one data format to another is called a gateway. A gateway is a network device that connects dissimilar networks. It establishes an intelligent connection between a local network and external networks with completely. different structures. A gateway is a network device that connects dissimilar networks. It establishes an intelligent connection between a local network and external networks with completely. different structures.

32 Some examples of gateways include a router that translates data from one network protocol to another, a bridge that converts between two networking systems, and a software application that converts between two dissimilar formats. Some examples of gateways include a router that translates data from one network protocol to another, a bridge that converts between two networking systems, and a software application that converts between two dissimilar formats. The key point about a gateway is that only the data format is translated, not the data itself. In many cases, the gateway functionality is incorporated into another device The key point about a gateway is that only the data format is translated, not the data itself. In many cases, the gateway functionality is incorporated into another device. The gateway often acts as a proxy server and a firewall. The gateway often acts as a proxy server and a firewall.

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